This is the fifth in a series of reports that T2RL has produced on the transformation to the new Offer, Order, Settle, Deliver environment. One of the stated motivations for the change is to lower the barriers of entry for providers to the airline technology market. This should allow companies with expertise in modern retailing to provide services to airlines in competition with the traditional suppliers to the industry. A key determinant of whether such new vendors will be successful in the market is the extent to which they will be able to integrate their offerings into the overall airline IT landscape. This report assesses the current state of the market with a view to establishing a modular architecture of airline IT services that would allow the mixing of services from multiple providers.